As the Micro AIs are in a stable release for the first time in Wesnoth 1.12.0, they will now likely see much more usage both by content developers and by players. As a result, I expect that a number of bugs will we found that previously went undetected because they only occur rarely or under very specific circumstances. I will use this post as a reference for bugs found during the 1.12 series, together with information on when they were fixed and work-arounds.

Micro AI bugs in Wesnoth 1.12:

Big Animals:
Symptom: AI units do not attack when [avoid_unit] is not used.
Versions: 1.12.0. Fixed in 1.12.1.
Workaround: Use [avoid_unit] with an id set to a unit that does not exist. For example

Herding:
Symptom: Dogs sometimes wander off at end of turn.
Versions: 1.12.0-1.12.1. Fixed in 1.12.2.
Workaround: This is caused by the dogs having moves left under certain conditions and the default AI taking over. If the side has no other units than the herder/herded animals, this can be worked around by removing the CAs of the default AI.

Lurkers:
Symptom: Error message shows up on screen when an AI unit is ambushed (only when playing in debug mode).
Versions: 1.12.0. Fixed in 1.12.1.
Workaround: None needed as this is a false alarm. Just ignore the message (or don't play in debug mode if it bothers you). It will not appear any more starting from 1.12.1 (even in debug mode).

Stationed Guardian:
Symptom: Error message on screen (and MAI is abandoned) if station is set to an unreachable position.
Versions: 1.12.0. Fixed in 1.12.1.
Workaround: Don't use an unreachable hex for the station. In fact, if done that should be considered a bug in the scenario rather than in the Micro AI, but it was "fixed" anyway as the MAIs should never produce error messages (within reason).